U.S. Pat. No. 3,921,825 issued Nov. 25, 1975, to Robert T. Sheehan for Bag-Turning Stacking Palletizer discloses a palletizer in which substantially the entire machine is raised and lowered and also moved to and fro laterally of the direction of feeding the filled bags from a feed-on conveyor in order to raise the bag positioner to deposit each tier of bags, the bag positioner being likewise rotatable to position the bags of each tier according to a predetermined pattern which is varied from tier to tier in order to overlap the joints between the bags in the tier immediately below the tier of bags being laid. Typical bag arrangements for different tiers are shown in FIGS. 10 to 13 of that patent, and can be reproduced by the present palletizer. In the said Sheehan U.S. Pat. No. 3,921,825, however, the mechanism which supports and rotates the bag-positioning carriage has to be raised and lowered bodily because the pallet remains at a constant level.
In contrast, the palletizer of the present invention has a more simplified construction which enables the rotary bag-positioner to remain at a constant level while the pallet elevator is lowered from its highest position immediately beneath the gates of the bag-positioner for depositing the lowermost tier of bags step-by-step to successively lowered positions for depositing each subsequent tier until its lowermost position for depositing the uppermost tier of bags thereon is reached. The palletizer of the present invention, by thus greatly simplifying the construction, also greatly increases the speed of operation of the mechanism and reduces the amount of power required, in contrast to the much slower operation of the machine shown in U.S. Pat. No. 3,921,825 and the greater amount of power required to operate it. Moreover, the palletizer of the present invention provides an empty pallet stack in a magazine immediately adjacent the pallet elevator in the same frame structure mounted on the same ground wheels and adjacent the hydraulic pumping and valve equipment and the driving motors, and the operator controls the machine from a console at a control station on the machine so that the entire present machine moves as a unit to its different positions in contrast to the above-mentioned prior patented palletizer wherein the pallet magazine and the hydraulic and electrical equipment are mounted as separate units and no unitary movement of the entire machine is possible or practical.